//测试常量
package Constant;

public class Constant {
    public static void main(String[] args) {
        final double PI=3.14;//常量命名规则:由大写字母和下划线构成
        double r=4;
        double area=PI*r*r;
        double circle=2*PI*r;
        System.out.println("圆的面积:"+area);
        System.out.println("圆的周长:"+circle);
    }
}
